1. Field of the Invention
The invention relates to high density electrical connectors and specifically to low insertion force connectors that are specially suited for repetitive coupling and uncoupling.
2. Prior Art
Interconnection of electronic devices such as integrated circuits and printed circuit boards becomes increasingly difficult as the number of contacts increases and as the number of times the insertion and removal of the devices increases. As the number of contacts increases, the alignment and the cleanliness of the contacting surfaces becomes more critical. As the number of interconnections increases, the potential for wear and/or damage to the connector through mating and de-mating becomes greater.
It is commonly known to insert a circuit board into connectors having individual, spring-loaded retaining contacts in order to provide a removable connection. As the number of contacts increases, the amount of force required to overcome the cumulative resistance of the corresponding number of sockets becomes so great that the potential for damage to either the connector or the circuit board becomes far more likely. The insertion and removal force encountered is generally borne by the surfaces that are in rubbing contact during the manipulative step. For example, in U.S. Pat. No. 4,826,446 to Juntwait, individual contact pins having spaced flexible contact arms are adapted to receive and to be flexed apart by an electrical component, such as a printed circuit card, that is inserted and pivoted therein. Although the connector significantly reduces the amount of force needed for insertion, the normal forces at the point of contact on the contact arms and on the card nonetheless eventually cause wear upon each insertion and removal of the card.
U.S. Pat. No. 3,102,767 to Schneck discloses an electrical connector for flat conductor cable where the cable is wrapped around a U- or channel-shaped spring. The dielectric coating of the cable is stripped to expose the conductor ribbons which are forced into contact with component boards upon insertion between the arms of the spring. The forces of insertion and removal in this device are endured by the conductors and the contact circuitry on the surface of the component boards. U.S. Pat. No. 3,319,216 to McCullough discloses a similar structure wherein multiconductor cable and a printed circuit board are in rubbing contact with each other upon insertion and removal of the board.
U.S. Pat. No. 3,401,369 to Palmateer et al. discloses a laminated connector which includes a sheet of dielectric material and a plurality of electrical contact members for using printed circuit techniques. As can be seen in FIG. 5 of that reference, the contact pressure between the laminate and the member inserted therein is focused on conductive members on the insertion member and on contact buttons on the laminate. Such a construction will have limited multiple insertion and removal life. To overcome problems of alignment and insertion force, electrical connectors have been developed which use mechanical actuation to close (or open) contacts and to maintain a mechanical retaining force. Such devices are generally complex and bulky. More sophisticated actuation mechanisms using shape-memory alloy actuators have also been developed in which remote electrical actuation of the connector is provided.
None of the above-discussed connectors provides a concept for a simple, manually-operated, low insertion force, high density, multiple insertion connector with independent two-sided contact and contact wiping for a wide range of connector configurations, such as those discussed above, including connectors which provide for remote electrical actuation.